Baseball is one of the most popular sports in the United States but has a high incidence of throwing related shoulder and elbow injuries. Suggested contributors to injury include extrinsic participation factors such as lack of adequate rest and recovery, number and type of throws performed, and faulty throwing mechanics. Additionally, modifiable intrinsic physical characteristics such as scapular dysfunction, glenohumeral internal rotation deficits, tightness of the posterior capsule and musculature, and muscle imbalances and weakness are also suspected contributors to injury. While intrinsic factors are thought to be culprits for throwing related upper extremity injury, their contribution to injury have not been demonstrated in a prospective study. The primary purpose of this study is to prospectively identify whether there are modifiable physical characteristics present in throwers who subsequently sustain a throwing related injury and whether injury potential can be predicted based on clinical screening of these physical characteristics. Specifically, glenohumeral rotation range of motion, posterior shoulder tightness, shoulder girdle muscle strength, and scapulohumeral motion will be assessed prospectively in a cohort of high school baseball players from 30 baseball teams (600 athletes) across central North Carolina. Group comparisons will be made between the participants who sustained a throwing related shoulder or elbow injury and those who were injury free. Regressions will be used to determine what physical characteristics are predictive of sustaining a throwing related shoulder or elbow injury in the high school baseball players. PUBLIC HEALTH RELEVANCE: Project Narrative This project will identify potential contributors to throwing related injury to the shoulder and elbow. Fortunately for clinicians, these contributors can be quickly screened for during pre-participation screenings and modified through rehabilitation. If in fact that these physical adaptations are shown to be present prior to injury and are predictive of whether someone might get injured, then pre-participation screening can be performed and injury prevention programs implemented in hopes of decreasing injury.